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When to use Pressure Sensors for Level Measurement

September 8, 2011 by Kelvin Findlay

Your Guide to Level Measurement with Pressure Sensors

Inexpensive, simple, easy, effective, and stable are words not often used correctly in the same breath. However, when it comes to measuring liquid levels with pressure sensors, we can say all of that with confidence.

Pressure transducers measure level by detecting the pressure exerted by a certain volume of liquid at the bottom of the tank or well. This is then converted to a level based on a few factors including: tank type and size, and the specific gravity of the liquid.

Other than pressurized tank environments, the only changing variable here is specific gravity, which is affected by large swings in temperature. This, however, is easily fixed with temperature compensation internal to the pressure sensor.

With only one variable to deal with, measuring levels with pressure is accurate, stable, and effective in non-pressurized tank environments. Pressure sensors themselves are less expensive than the purpose-built alternatives. And using pressure sensors is definitively easy and void of any mentionable complexity.

Additionally, there are a host of process fittings for practically any mounting need, even 3A compliance. Therefore, as a general rule, liquid level measurement with pressure sensors is a good way to go.

There are certain applications where using a pressure sensor to detect liquid level is particularly appropriate. Turbulence, foam, vapor layers, and physical obstructions are all common occurrences in the world of tanks and liquids, and can negatively affect other level sensors. Pressure sensors, however, are not affected by any of these, and are a great alternative in such applications.

For pressurized tanks, using pressure sensors is still a viable option. However, it is a bit more complex and typically requires more than one sensor.